The conventional technical method of producing organolithium compounds (Kirk-Othmer, "Enc. Chem. Techn.", Vol 12, p. 547, 1967) is based on the reaction of lithium metal with organic halogen compounds, in which organolithium compounds as well as lithium halides are produced: EQU RX+2 Li.fwdarw.RLi+LiX (1)
X=Cl, Br, I PA1 R=allyl, benzyl PA1 R'=phenyl, mesitoyl PA1 X=Cl, Br, I
Allyllithium and benzyllithium compounds may among others be produced by the splitting of the corresponding ether derivative or acyloxy derivative with lithium metal (J. A. Katzen-ellenbogen R. S. Lenox, J. Org. Chem., 38, 326, 1973; U. Schollkopf in "Methoden der Organischen Chemie", Houben-Weyl, XIII/1, P. 161; J. J. Eisch, A. M. Jacobs, J. Org. Chem. 28, 2145, 1963): EQU ROR'+2Li.fwdarw.R-Li+R'OLi (2)
From the organolithium compounds so produced, numerous other organolithium compounds may be obtained by means of metal-H exchange: EQU R-Li+R'H.fwdarw.R-H+R'-Li (3)
or by means of metal-halogen exchange (D. Seebach. K.-H. Geiss in "New Applications of Organometallic Reagents in Organic Synthesis", p.1, Elsevier, 1976): EQU R-Li+R'-X.fwdarw.R'-Li+R-X (4)
Only in exceptional cases had it heretofore been possible to synthesize organolithium compounds directly from lithium metal and hydrocarbons. Thus, for instance, 1-alkines (H. Ogura, H. Takashi, Synth. Commun., 3 135, 1973), triphenylmethane or acenaphtylene (B. J. Wakefield, "The Chemistry of Organolithium Compounds", p. 70, Pergamon Press, 1974) may be lithiated with metallic lithium. According to D. L. Skinner et al (J. Org. Chem., 32, 105, 1967) lithium reacts with 1-alkenes in the absence of a solvent to produce 1-alkinyllithium compounds and lithium hydride: EQU RCH.dbd.CH.sub.2 +4 Li.fwdarw.RC.tbd.C-Li+3 LiH (5)
whereby 1-lithio-1-alkenes are produced as byproducts of the reaction, at very small yields. In the presence of tetrahydrofuran (THF) 1-lithio-1-hexene was obtained from lithium and 1-hexene at boiling temperatures, at 9% yield.
A procedure for the preparation of organolithium compounds from lithium and ethylene in dimethoxymethane or THF in the presence of biphenyl and, if the case, naphthalene was recently made known (V. Rautenstrauch of Firmenich S. A., Geneva, Swiss Pat. No. 585, 760, May 20, 1974; V. Rautenstrauch, Angew, Chem., 87, 254, 1975). The yields of organolithium compounds according to these procedures are at very low levels. Since the reaction products furthermore occur in the form of a mixture of vinyllithium and 1,4-dilithiobutane, this procedure hardly seems suitable for technical purposes.